The body includes various passageways such as arteries, other blood vessels, and other body lumens. These passageways sometimes become occluded by a tumor or restricted by plaque. To widen an occluded body vessel, balloon catheters can be used, for example, in angioplasty.
A balloon catheter can include an inflatable and deflatable balloon carried by a long and narrow catheter body. The balloon is initially folded around the catheter body to reduce the radial profile of the balloon catheter for easy insertion into the body.
During use, the folded balloon can be delivered to a target location in the vessel, e.g., a portion occluded by plaque, by threading the balloon catheter over a guide wire emplaced in the vessel. The balloon is then inflated, e.g., by introducing a fluid into the interior of the balloon. Inflating the balloon can radially expand the vessel so that the vessel can permit an increased rate of blood flow. After use, the balloon is deflated and withdrawn from the body.
In another technique, the balloon catheter can also be used to position a medical device, such as a stent or a stent-graft, to open and/or to reinforce a blocked passageway. For example, the stent can be delivered inside the body by a balloon catheter that supports the stent in a compacted or reduced-size form as the stent is transported to the target site. Upon reaching the site, the balloon can be inflated to deform and to fix the expanded stent at a predetermined position in contact with the lumen wall. The balloon can then be deflated, and the catheter withdrawn.
One common balloon catheter design includes a coaxial arrangement of an inner tube surrounded by an outer tube. The inner tube typically includes a lumen that can be used for delivering the device over a guide wire. Inflation fluid passes between the inner and outer tubes. An example of this design is described in Arney U.S. Pat. No. 5,047,045, the entire contents of which is hereby incorporated by reference.
In another common design, the catheter includes a body defining a guide wire lumen and an inflation lumen arranged side-by-side. Examples of this arrangement are described in Wang U.S. Pat. No. 5,195,969 the entire contents of which is hereby incorporated by reference.